1. Field of the Invention
The present invention relates to repairing lost circulation zones in a wellbore. More specifically, the invention relates to restoring a lost circulation zone in a wellbore with an annular member with side walls having perforations.
2. Description of the Related Art
Hydrocarbon producing wellbores extend subsurface and intersect subterranean formations where hydrocarbons are trapped. The wellbores are created by drill bits that are on the end of a drill string, where typically a top drive above the opening to the wellbore rotates the drill string and bit. Cutting elements are usually provided on the drill bit that scrape the bottom of the wellbore as the bit is rotated, and excavate material thereby deepening the wellbore. Drilling fluid is typically pumped down the drill string and directed from the drill bit into the wellbore; where the drilling fluid then flows back up the wellbore in an annulus between the drill string and walls of the wellbore. Cuttings are produced while excavating and are carried up the wellbore with the circulating drilling fluid.
While drilling the wellbore mudcake typically forms along the walls of the wellbore that results from residue from the drilling fluid and/or drilling fluid mixing with toe cuttings or other solids In the formation. The permeability of the mudcake generally isolates fluids in the wellbore from the formation. Seepage of fluid through the mudcake can be tolerated up to a point. Occasionally cracks form in a wall of the wellbore, where the cracks generally are from voids in the rock formation that were intersected by the bit. Cracks in the wellbore wall sometimes can also form due lo differences in pressure between the formation and the wellbore. Fluid flowing from the wellbore into the formation is generally referred to as lost circulation. If the cracks are sufficiently large, they may allow a free flow of fluid between the wellbore and any adjacent formation. If the flow has a sufficient volumetric flow rate, well control can be compromised thereby requiring corrective action.